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GAINESVILLE, Fla. --- The appearance of the American crocodile in popular Biscayne Bay after 25 years marks the comeback of the reptile from near-extinction in South Florida, says a University of Florida researcher.

Nesting has been spotted in Biscayne Bay north of Homestead for the first time in a century and young crocodiles -- rarely seen on other public parts of the large water body since the 1970s -- now mix with people in parks and on golf courses, said Frank Mazzotti, a UF professor of wildlife ecology and conservation.

"The crocodiles' recovery really symbolizes the success of the Endangered Species Act and the efforts on the part of many agencies and groups to preserve mangrove habitat and to restore flow of freshwater to estuaries in South Florida," he said. "One of the consequences is that crocodiles now occur in areas where people occur and have become the No. 1 nuisance wildlife endangered species phone call received by the Florida Game and Fresh Water Fish Commission," he said.

In a series of night spotlight surveys in Biscayne Bay and Card and Barnes sounds between 1996 and 1998, Mazzotti and Michael Cherkiss, a UF graduate student in wildlife ecology and conservation, counted a total of 102 crocodile sightings and found two nests.

South Florida is unique in that it is the only place in the United States where the American crocodile lives and the only place in the world where both alligators and crocodiles are found, Mazzotti said.

When the American crocodile was declared an endangered species in 1975, they were found primarily in Everglades National Park and north Key Largo, Mazzotti said. By the late ‘70s, crocodiles were beginning to thrive at the Turkey Point Power Plant in Florida City, where the construction of cooling canals and berms created ideal nesting areas, he said.

Baby crocodiles are less tolerant of salt water than adults and grow much more quickly in brackish water, Cherkiss said. After cooling canals were extended from the power plant into the surrounding mangrove swamp, crocodile nests multiplied, he said.

"Biscayne Bay is perfect for smaller crocodiles because the mangroves provide cover, the canals and inland lakes and ponds provide low salinity water and there are few adults around to chase them off into marginal habitats," Cherkiss said.

Nearly all of the crocodiles the UF researchers tagged were juveniles, he said.

Similar efforts to restore fresh water to estuaries in Everglades National Park as part of an even larger project have helped to increase numbers of crocodiles there, Mazzotti said.

Historically, crocodiles have appeared as far north as Lake Worth on Florida's east coast, Mazzotti said. While these large reptiles were once seen on the Gulf coast as far north as Sanibel Island, nests only recently reappeared there, he said.

"One indication of the continued recovery of this endangered species is there happens to be a crocodile nesting on Sanibel Island during the past few years, as well as at Marco Island Airport," he said.

The big test for the crocodiles' future survival in Biscayne Bay is whether humans, who fish, boat and swim there in large numbers, learn to accept them, he said.

"People should not fear crocodiles," Mazzotti said. "But they should certainly have every respect for them."

Unlike its cousins in Africa and Australia, the American crocodile is not a belligerant species and is even less aggressive than the American alligator, Mazzotti said. "The only time these crocodiles present problems is when people feed them," he said. "Then they not only become used to humans, they associate humans with food. Unfortunately, they don't know where the handout ends and the hand begins, and that gets them into trouble."

Story Source:

The above story is based on materials provided by University Of Florida. Note: Materials may be edited for content and length.

University Of Florida. "UF Study: Near-Extinct Crocs Make Comeback In Popular Biscayne Bay." ScienceDaily. ScienceDaily, 16 June 1999. <www.sciencedaily.com/releases/1999/06/990615154654.htm>.

University Of Florida. (1999, June 16). UF Study: Near-Extinct Crocs Make Comeback In Popular Biscayne Bay. ScienceDaily. Retrieved March 31, 2015 from www.sciencedaily.com/releases/1999/06/990615154654.htm

University Of Florida. "UF Study: Near-Extinct Crocs Make Comeback In Popular Biscayne Bay." ScienceDaily. www.sciencedaily.com/releases/1999/06/990615154654.htm (accessed March 31, 2015).

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